Method of making an imaging member

ABSTRACT

STRATE THEREBY FORMING A LAYER OF PARTICULATE MATERIAL DISPERSED IN SAID SOFTENABLE PLASTIC.   THE METHOD OF MAKING AN IMAGING MEMBER COMPRISING COATING, PREFERABLY BY CASCADING, A DISPERSED LAYER OF PARTICULATE MATERIAL OVER A SOFTENABLE PLASTIC SUBSTRATE WHICH IS SOFTENED ALLOWING THE PARTICULATE MATERIAL TO EMBED BELOW THE SURFACE OF SAID SOFTENABLE PLASTIC SUB-

June 20, 1972 W. L` GOFFE METHOD OF MAKING AN IMAGING MEMBER Filed Aug.28, 1969 OO OOO OOO O ooo ooo ooo ooo oo INVENTOR. `W ILLIAM L. GOFFE A7' TORNE Y United States Patent Oflice 3,67l,282 Patented June 20, 1972Int. Cl. B44d 1 094 U.S. Cl. 117-16 34 Claims ABSTRACT OF THE DISCLOSUREThe method of making an imaging member comprsing coating, preferably bycascading, a dispersed layer of particulate material over a softenableplastic substrate which is softened allowing the partculate material toembed below the surface of said softenable plastic substrate therebyforming a layer of particulate material dispersed in said softenableplastic.

CROSS REFERENCE OF RELATED APPLICATIONS This application is acontinuation-in-part of my copending applications (1) Ser. No. 570,996,filed Aug. 8, 1966 now abandoned which s a continuation-in-part of mycopending application (2) Ser. No. 483,675, filed Aug. 30, 1965, whichcopending application (2) is in turn a continuation-in-part of myapplication (3) Ser. No. 403,002 filed Oct. 12, 1964 and now abandoned.

BACKGROUND OF THE INVENTION This invention relates to imaging and inparticular to a novel method of forming an imaging member.

In the art of Xerography, a Xerographc plate containing aphotoconductive insulating layer is first given a uniform electrostaticcharge in order to sensitize its surface. The plate is then exposed toan image of activating electromagnetic radiation such as light, X-ray orthe like which selectively dissipates the charge in the illuminatedareas of the photoconductive insulator, while leaving behind a latentelectrostatic image in a non-lluminated area. The latent electrostaticimage may be developed and made visible by depositing finely dividedelectroscopic marking particles on the surface of the photoconductiveinsulating layer. This concept was Originally disclosed by Carlson inU.S. Patent 2,297,691, and is further amplfied and described by manyrelated patents in the field.

One form of a Xerographic plate consists of a photoconductive layercomprising a substantially insulating organic resin binder havingdispersed therein finely divided particles of an inorganicphotoconductive insulating material. This form of photoconductive plateis described in U.S. Patent 3,121,006 to Middleton et al., and otherrelated patents in the field. The binder plate shown by Middleton etal., can be formed by any convenient method such as those set forth inthe disclosure of the above patent. These methods include forming amixture of slurry of the materials which form the binder plate, andpainting, pouring, dipping or spraying the material onto a suitablesubstrate to form the desired thickness of the photoconductive binderlayer on the substrate. The above methods, of necessity, involve forminga mixture of a slurry of the nert resinous binder material and theinorganic photoconductive insulating material, and other necessaryingredients, in order to form the binder plate. In addition, the abovemethods result in a somewhat uneven control of the thickness of thephotoconductive binder layer. Also, certain photoconductive particlesmay be dissolved, recrystallize, or chemically react adversely withparticulate solvents and other chemical additives'in the slurry, andmust be excluded from the above techniques necessary in manufacturing abinder plate.

In addition to the xerographic binder plates described above, imagingmembers are also used in a new migration imaging system embodiments ofwhich are described in applicant's copending application Ser. No.483,675 and described in applicant's copendng application Ser. No.460,377, filed June 1, 1965 now U.S. Patent No. 3,520,- 681 which is acontinuation-in-part of applicant's copending application Ser. No.403,002, filed Oct. 12, 1964, now abandoned.

A limiting factor in the resolution of the images produced by an imagingprocess is the quality of the imaging member. Some of the problems ofmaking an imaging member useful in migration imaging are similar tothose described above in the manufacture of binder plates for use inxerography. A problem encountered in manufacture of migration imagingmembers is keeping the particulate materials from agglomerating in theimaging member. Particulate materials have a tendency to cluster oragglomerate, thus, giving the etfect of using variable sized particulatematerials. Such agglomeraton reduces the resolution capabilty of theimaging process.

There is, therefore, a need for a more simplified method of manufacturnga binder layer or plate having the desired properties and yet whichobviates the disadvantages of the methods mentioned above.

SUMMA RY OF THE INVENTION It is, therefore, an object of this inventionto provide a novel method of forming an imagirg member.

It is another object of this invention to provide an improved imagingmember.

It is a further object of this invention to provide an improved systemfor producing a layer of material having a photoconductive materialdispersed in a binder.

It is yet another object of this invention to provide an improved systemof producing a layer of material having a conductive material dispersedin a binder.

It is another object of this invention to provide a novel method ofproducing a binder layer having an insulating material dispersed in abinder.

The foregoing object and others are accomplished in accordance with thisinvention by providing a novel method of producing an imaging member bycoating by conventional techniques, such as those demonstrated in U.S.Patents 3,070,90O and 3,212,'888; a dispersed layer of conductive,photoconductive or insulating particles over a softenable resinousplastic substrate so as to form a layer of the particles in saidsoftenable film. In one form of this invention, the softenable film isthen softened as by heat or vapor treatment allowing the depositedmaterial to embed into and below the surface of the softened plastic.This sequence is followed by another cycle of coating and softeningwhereby after a pluralit-y of such cycles, a uniform, dense orconcentrated deposition of particles i-s formed in the softenablesubstrate or binder. Binder layers may be made with the desiredparticles dispersed throughout the plastic matrix, or concentrated inone or more planar sections of the layer.

Depending upon the method employed to place the coating of particulatematerial upon the softenable plastic substrate, the substrate may or maynot be allowed to harden prior to the subsequent coating of the surface.In most instances it will be desirable to allow the substrate to hardenat least partially before another cycle of coating and softening of thesubstrate to aid in dispensing another coating of particles on thesurface. By utilizing a plurality of coating and softening steps, theoccurrence of agglomeration or clustering of the particulate material isavoided or greatly reduced. Surprisingly, the particulate material doesnot agglomerate within the plastic substrate although the particulatematerial becomes very dense or concentrated in accordance with theprocess of this invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages of this invention willbecome apparent upon consideration of the following disclosure of thisinvention; especially when taken in conjunction with the followingdrawings wherein:

FIG. 1 is a schematic illustration of one method of making an imagingmember contemplated by this invention.

FIG. 2 is a schematic illustration forming an imaging member.

FIG. 3 is a. schematic illustration of the second stage in forming animaging member.

FIG. 4 is a schematic illustration of the third stage in forming animaging member.

FIG. 5 is a view of one embodiment of a finished imagig member ascontemplated by this invention In FIG. 1 reference character denotes aconventional imaging member comprising an insulating substrate 11 havinga conductive metallic overcoatng 12, and -a softenable plastic layer 13overlaying layer 12. The imaging member is formed preferably bycascading conventional carrier beads 14 having the desired particles tobe coated 15, triboelectrically attracted to said carrier beads andbeing cascaded over the surface of the softenable plastic layer 13,whereby a sparse substantially uniform layer of the desired coatingmaterial 15 is formed on the surface of the softenable plastic layer 13,as shown in FIG. 2. To avoid the formation of agglomerates or clustersof particulate material, the coating applied to the plastic substrate iscontrolled so as to be, although substantially uniform, dispersed inrelation to the area to be coated. That is, it has been found thatagglomerates are avoided by applying to the plastic substrate a uniformbut scatof the first stage of tered or dispersed layer of particulatematerial so as to the amount of particulate material on the carrierbeads i and the amount of carrier beads being cascaded over the surfaceof the substrate, a dispersed or scattered uniform 'layer is easilyprovided. By limiting the amount of particulate material on the carrierbeads, a plurality of cascading Operations can be carried out betweeneach embedment of the particles into the plastic substrate. According'-ly, it is possible to cascade particulate material on carrier beads overthe plastic substrate from two to about twenty times before embeddingthe coating of particles below the surface of the substrate. Obviouslythere is a balance to be struck between the amount of particulatematerial placed upon the surface of the substrate prior to embedment andthe number of times the cycle of coating and 'embedment is to berepeated. In any case, the coating is adequate for the purposes andobjectives of this invention if the majority of particulate material isnot piled up on one another prior to being embedded below the surface ofthe plastic substrate. A near monolayer of particulate materal coverngthe plastic substrate is preferred but care must be taken not to exceeda monolayer causing a piling The plastic layer 13 is softened by anyconvenient means such as by Chemical vapors or liquids, or heat, so asto allow the deposited material 15 to snk into the softened plastic asshown in FIG. 3. Any softening means which only effects the plasticlayer is suitable. The cascading step illustrated in FIG. l is thencarried out again forming another substantially uniform layer ofparticles 15 on layer 13 as shown in FIG. 4. The softenable layer 13 isagain softened as described in FIG. 3 so as to build up another layer ofparticles'in the softenable plastic matrix 13. This process ofcascading, softening, and then cascading again, is carried outanydesired number of times until a sufficient thckness of cascadedparticles15 are built up in the softenable plastic matrix layer 13. This processresults in a final plate such as that illustrated in FIG. 5 containing acoated substrate having thereon a layer comprising particles 15dispersed in a plastic matrix 13.

The substrate upon which the softenable plastic is laid may be anyconventional imaging type substrate such as a plastic film overcoatedwith a thin film of aluminum. Any suitable xerographic substrate knownto the art may be used. Typical substrates include a metallic sheet, aweb, foil, cylinder, or the like; a sheet of glass with an electicallyconductive coating, or a conductive coated sheet of paper or stableplastic. In the art of xerography, the conductive substrate in someinstances may be deleted, if desired, and an insulating base used, or insome cases no substrate employed at all. If imaging systems other thanXerographic are used, the substrate may be either a conductor as definedabove, semi-conductor or an insulator such as paper or plastic.

The softenable plastic material of layer 13 may be any suitable materialwhich is heat, solvent vapor, or liquid softened. Suitable materials areStaybelite Ester 10, a difty percent hydrogenated glycerol rosin esterof the Hercules Powder Co., Piccotex 100, a styrene-type resin ofPennsylvania Industrial Chemical Co.; Araldite 6060 and 6071, epoxyresins of CIBA; Velsicol X-37, Velsicol Chemical Corporation. Othersoftenable materials useful in the practice of this invention are listedin copendng application Ser. No. 837,780 filed June 30, 1964 which isincorporated heren by reference. This group of plastic materials is notintended to be limiting, but merely illusrtative of materials suitablefor the plastic matrix. The plastic layer may be of any suitablethckness, electrically conductive or non-conductive. The plasticsubstrate may be as thin as 1 to 4 microns in thckness, with no'limitations on the maximum thckness.

Typical solvents include without limitation; cyclohexane, Freon 113,Sohio Odorless Solvent 3440, pentane, heptane, toluene,trichloroethylene, methyl ethyl ketone, methylene chloride, acetone,etc. Exposure to the above solvents need only be as long as necessary tosoften the plastic substrate. Times ranging from about a fewseconds orless up to about 30 seconds, depending upon the softening effect of theparticular solvent, are usually sufficient. Vapor softening is preferredover softening by immersng in the liquid solvent in that liquid solventsmay dissolve the substrate unless the exposure' is carefully controlled.

When heat is used to soften the plastic substrate, the temperature needonly be as high as that necessary to allow the particulate material toembed into the plastic. Temperatures are usually in the range of about60' to C. Times up to several minutes are usually suflicient.

The particles 15 which constitute the remaining portion of the binderlayer may comprise any suitable photoconductive, conductive orinsulating material. Typical photoconductors are amorphous selenium, anyof the inorganic photoconductive pigments disclosed in U.S. Pat.3,121,006 to Middleton et al., which include zinc oxde, zinc sulfide,cadmium sulfide, cadmium sulfoselenide and many others, compounds ofarsenic and selenium, organic photoconductors including azo dyes, suchas Watchung Red B (E. I. du Pont de Nemours & Co.), quinacridones, suchas Monastral Red B (E. I. du Font), commercial indigo (National AnalineDivision of Allied Chemical Co.); cadmium yellows, such as Lemon CadmiumYellow X-2273 (Imperial Color and Chemical Dept. of Hercules Powder Co.)and cadmium sulfide (General Electric Co.)', phthalocyanine;N-2"-pyridyl- 8,13 dioxodinaphtho-(l,2-2',3')-fura 6 carboxamide(prepared in accordance with patent application Ser. No. 42 1,2811-cyano-2,3-( 3 '-nitro -phthaloyl-7,8-benzopyrrololine (prepared inaccordance with patent application Ser. No. 445,235);l-cyano-2,3-(3'-acetamido)-phthaloyl- 7,8-benzopyrrocoline (prepared inaccordance With patent application Ser. No. 445235),N-2"-pyridyl-8,l3-dioxodinaphtho-(l,2-2',3')-furan-6-carboxamide(prepared in accordance With patent application Ser. No. 42l,28l);selenium-tellurium alloys; quinacridonequinone (E. I. du Pont de Nemours& Co., Inc.); polyvinyl carbazole; and mixtures thereof.

If the binder layer is desired to be used for purposes other thanxerographic, the particles 15 may be conductive or insulating dependingon the structure desired. Any suitable insulating or conductve particlesor pigments may be used. Typical materials are carbon black, garnet,iron oxide, pigment dyes such as prusson blue, and many other materials.

The carrier bead material 14 may comprise any suitable conventionalcarrier known to the art. Typical carrers are glass beads, plasticcoated metal, coated glass, etc. The only requirement necessary inregard to the cascade material is that the proper triboelectricrelationship between the carrier bead and "toner or particulate materialbe met. In general, the particle size of the carrier beads are up toabout 700 microns in diameter. U.S. Pats. 2,6l8,551 and 2,638,416 toWalkup; and 2,6l=8,552 to Wise are illustrative of typical carriermaterials suitable for use in the method of this invention.

Usually the method of this invention results in the particles beingdispersed in a layer to a depth of about M to of the thickness of thesoftenable plastic layer. The size of the particulate material isnormally small in comparison with the thickness of the plasticsubstrate, ranging in size up to about 30 microns in diameter. Usually,however, the particulate material ranges in size of about .01 to about 5microns or less in diameter with much of the material beingsubmicroscopic in size depending on the desired imaging member to beformed. For optimum image density, the particles size is below anaverage of about 0.7 micron. Obviously, there must be maintained somerelationship between the size of the particulate material and thethickness of the softenable plastic substrate. That is, the size of theparticle material must certainly not exceed the thickness of thesubstrate and desirably the diameter of the particles are not greaterthan about half the thickness of the softenable plastic layer.

In other embodiments of this invention, the desired particulate materialmay be coated on the surface of the plastic substrate by dusting,spraying, vapor condensation, dipping in a fluidzed bed etc. As incascading, the coating step is repeated between each softening step andthe amount of particulate material is maintained low so as to provide adispersed coating on the surface of the substrate at any one time. Inaddition, the plastic substrate may remain soft during the coatingoperation depending, of course, on the coating method selected.

DESCR IPTION OF THE PREFERRED EMBODIM ENTS The following examplesfurther specifically define the present invention with respect to themethod of forming an imaging member. The percentages in the disclosure,examples and claims are by weight unless otherwise indicated. Theexamples below are intended to illustrate the various preferredembodiments of making a binder layer by cascade technique.

The examples below illustrate the novel method of forming a binder plateas contemplated by this invention, wherein a series of plates are madeusing a photoconductive grade zinc oxide pgment dispersed in asoftenable plastic binder.

In the examples, in order to attain maximum photosensitivity, threedifferent mixtures of zinc oxide particles were sensitized withRhodamine B dye available from Eastman Kodak Company of Rochester, N.Y.The zinc oxide used was a photo-conductve grade zinc oxide material soldunder the name Florence Green Seal available from the New Jersey ZincCompany. These mixtures are designated A, B and C, respectively, and arelisted below in Table I.

TABLE I Mixture A-25 ml. methyl alcohol, .03 gram of Rhodamine B, 8grams of zinc oxide Mixture B-25 mlliliters of methyl alcohol, .15 gramof Rhodamine B, 8 grams of zinc oxide Mixture C-25 mlliliters of methylalcohol, .20 gram of Rhodamine B, 8 grams of zinc oxide.

The procedure for dyeing the zinc oxide comprises placing variousamounts of zinc oxide and Rhodamine B dye in 25 ml. of methyl alcohol.The solution is then poured onto filter paper to dry. The resultingpaste is stirred until all the alcohol has evaporated. The mixture isthen baked for about 1 hour resulting in a dyed zinc oxide powder.

The carrier beads consist of glass beads 50 microns in diameteravailable from Potters Brothers, Inc. The cascading mixture used in theexamples consists of a .12 gram ratio of zinc oxide mixture (dyed withRhodamine B) and 50 grams of glass beads.

Example I A strip of aluminized Mylar designated Sample 1, consisting ofa micron layer of Myler overcoated with a submicron layer of aluminum,which has a 2 micron rollcoated overlayer of a softenable plastic.Staybelite 10` thereon, is fixed to the bottom of a rectangular 2 x 6 x4 nch brass container. The container is rotated about its horizontalaxis and cascaded with a mixture of .12 gram of Florence Green Seal zincoxide particles dyed with .03 gram of Rhodamine B per 8 grams of zincoxide, and 50 grams of 50 micron diameter glass beads. The developermaterial' consisting of carrier beads and zinc oxide particles, iscascaded over the aluminized Mylar strip held to the bottom of thecontainer for 10 rotations of cascades. The strip is removed from thecontainer and heated to C. for two minutes, re-fixed in the container,and cascaded again. This cycle is repeated 6 times after which a zincoxide binder layer has been formed With the zinc oxide particlesdispersed approximately half way through the thickness of the softenableStaybelite plastic.

Example II Five additional strps designated Samples 2-6 are formed bythe method of Example I using various mixtures as set forth in Table Iand varying number of layers and cascades per layer. The mixtures,number of layers, and cascades per layer are illustrated in Table IIbelow for Samples 1-6, inclusive.

TABLE II Temp. for

Number Cascades Time for heat fix, ol layers per layer heat fix 80 C.

6 10 2 minutes 80 8 ?JO do 80 Example III Example IV Sample 2 of TableII is treated by the imaging method of Example III by charging to aninitial negative potential of 130 volts, and exposed to a light source.of 11.2 footcandle-seconds. r

Example V sample 3 of Table II is treated by the method of Example IIIby charging to an initial negative potential of 140 volts and exposed toa light source of 11.2foot-candleseconds.

Example VI Sample 4 of Table II is imaged by the method of Example IIIby charging to an initial negative potential of 150 volts and exposingto a light exposure of 84 foot-Candleseconds.

The potential drop after exposure to the various light sources mentionedin the above examples for Examples 1, 2, 3 and 4 as measured with auelectrometer probe are shown in Table III below.

TABLE III Potential drop due Light Initial to light exposure inpotential exposure footcandlein volts in volts seconds Example VII Astrip of Staybelite coated 2 microns thick over a layer of aluminizedMylar is prepared as described in Example I. The strip is placed face upon a heated surface and heated to about 80 C. A powder cloud of charcoalcontaining 8.7X10- gms. of charcoal per liter of air is blown on to thesurface of the softened Staybelite for a period of seconds whereupon thecharcoal particles become attached to the Staybelite. After delaysufficient to allow the particles to become fully embedded below thesurface, this procedure is repeated five times during which thesubstrate remains heated. The thus formed imaging member is imaged anddeveloped in accordance with the procedure of Example VIII to produce avisible replica of the electrostatic image.

Example VIII An imaging member is made by first roll-coating a sheet ofaluminized Mylar polyester film with a layer of Piccotex 100approximately 2 microns in thickness. A mixture of air spun graphiteparticles (Type 200-19, The Joseph Dixon Crucible Co., Jersey City, NJ.)and 50 micron glass beads is then cascaded across the surface of theresin layer to form a sparse layer of the particles. The surface isheated to slightly above 100 C. whereupon the particles sink below thesurface of the layer. Thisprocess is repeated until the graphiteparticles have been dispersed in the layer to a depth of approximately 1micron.

An electrostatic image is applied to the member by means of a coronadischarge devce and a stencil. The image areas are positively charged toabout 60 volts; The

latent image-hearing member is then treated with cyclohexane vaporresulting in migration of the charged areas of particles to the surfaceof the polyester film'. Nonimaged portions of particles and the layer ofPiccotex are then removed by immersing the developed plate in liquidcyclohexane for about 10 seconds. The result is a faithful visiblereplica of electrostatic image.

Examples IX-XI I 3 The procedure of Example VIII is carried out `with aseries of imaging members to which are applied electrostatic images of2, '20, '40 and 160 volts, respectively, instead of 60 volts as inExample VHI. Faithful visible replicas of the electrostatic image areproduced. v i

nxam es XIILXXIX A series of seventeen imaging members is prepared bycascading a mixture of graphite particles (as used in Example VIII) and750 micron glass .beads several times across the surface of a two micronlayer of Staybelite 10 (Hercules Powder Company) overlying aluminizedMylar polyester film. The particles are embedded below the surface ofthe layer as in Example I. An electrostatic image is then formed on eachmember by means of a corona discharge device and mask, and the membersare developed immersion in liquid solverts'. to form faithful replicas,in accordance with .the following:

Appled potential volts: Solvent +40 Sohio Odorless Solvent 3440. +60 Do.+90 Do. Do. +180 Do. +40 Cyclohexane. +50 Do. +60 Do. +70 Do. +80 Do.+100 Do. +60 Freon 113. '+150 Do. V -40 Sohio Odorless Solvent 3440.V--SO Cyclohexane. -180 Do. -`300 Do.

a Thevinstant imaging process can also be cared out with the materialsand values shown below in Table IV. In each instance, the substratecomprses aluminized Mylar over which a layer of softenable material isroll coated. The particles in a plastic substrate is formed by thecascade method described above. Development is by immersion in solventliquid. The garnet particles used has an average diameter of about 5microns. v

TABLE IV Applied Soitenable layer potential Piccotex 100..

Particles' Solvent Neo Spectra carbon black (Columbau CarbonCyclohexane.

Freon 113. Cyclohexane. Freon 113. 7- Cyclohexane.

Do. Freon 113.

Sohio Odorless Solvent 3440. 6 Cyclohexane.

Do. Freon 113. Cyclohexane.`

The advantages of the above described invention enable imaging membersof constant quality to be made having thicknesses which can becontrolled to a much greater degree than binder plates made byconventonal techniques. In addition, photoconductive partcles whichheretofore were not possible to be incorporated in a resinous binder dueto a reaction with liquid solvents, etc. are now possible to be made bythis technique.

Although specific Components and proportionshave been stated in theabove description of a preferred embodiment of this invention, othersuitable materials and procedures such as those listed above, may beused with similar results. -In addition, other materials and changes maybe utilized which synergize, enhance or otherwise modify the particulatematerial or plastic substrate.

Other modifications and ramifications of the present invention wouldappear to those skilled in the art upon reading the disclosure. Theseare intended to be included within the scope of this invention.

What is claimed is:

l. A method of making an imaging member comprisng:

(a) coating a softenable plastic substrate with a substantially uniform,substantially unagglomerated dispersed layer of particulate materialhaving a diameter of up to about 30 microns,

(b) softening the substrate whereby the particulate material on saidsubstrate is allowed to embed below the surface, of said substrate, and

(c) repeating steps (a) and (b) a plurality of times whereby previouslyembedded particulate material further disperses in said substrate toprovide a substantally unagglomerated visible dsperso of said materialin said substrate.

2. The method of claim 1 wherein step (a) is repeated a plurality oftimes to build up the layer of particulate material to be embedded insaid substrate to no more than a monolayer.

3. A method of making an imaging member comprisrg:

(a) providing a softenable plastic substrate,

(b) cascading a particulate material having a diameter of up to about 30microns on a carrier material, over said layer, whereby a substantiallyuniform, substantially unagglomerated dispersed layer of the particulatematerial is formed on said substrate,

(c) softening said substrate whereby the particulate material on saidsubstrate is allowed to embed below the surface of said substrate,

(d)' hardening said substrate and,

(e) repeating steps (b), (c) and (d) at least once 'whereby previouslyembedded particulate material further disperses in said substrate toprovide a substantially uragglomerated visible dispersion of saidmaterial in said substrate.

4. The method of claim 3 wherein step (b) is repeated a plurality oftimes prior to each repeat of steps (c) and (d) to build up the layer ofparticulate material to be embedded in said substrate to no more than amonolayer.

5. The method of claim 3 wherein the plastic substrate is softened byheat.

6. The method of claim 3 wherein the plastic substrate is softened by avapor.

7. The method of claim 3 wherein the particulate material comprises aphotoconductor.

8. The method of claim 3 wherein the particulate material issubstantially nsulating.

9. The method of claim 3 wherein the particulate material comprises aconductive material.

10. A method of forming an maging member comprising:

(a) providing a member comprising a conductive substrate having thereona layer of softenable plastic material,

(b) cascading a particulate photoconductive material 10 having adiameter of up to about 30 microns carried on a plurality of carrierheads over said layer, whereby a substantially uniform, substantiallyunagglomerated dispersed layer of the particulate photoconductivematerial is formed on the surface of said softenable plastic material,

(c) softenng said softenable plastic material whereby thephotoconductive partcles on said softenable plastic material are allowedto embed below the surface of the softenable plastic layer,

(d) hardening said substrate and,

(e) repeating steps (b), (c) and (d) at least once whereby previouslyembedded particulate material further disperses in said substrate toprovide a substantially unagglomerated visible dispersion of saidmaterial in said substrate.

11. The method of claim 10 wherein the photoconductive materialcomprises selenium.

12. The method of claim 10 wherein the photoconductive materialcomprises znc oxide.

13. A method of making an maging member comprising:

(a) providing a softenable plastic substrate which overlays asubstantially conductive support,

(b) cascading a conductive particulate material having a diameter of upto about 30 microns carried on a carrier head over said plastic wherebya substantially uniform, substantially unagglomerated dispersed layer ofsaid particulate conductive material is formed on the surface of theplastic substrate,

(c) softening said plastic substrate whereby the particulate conductivematerial s allowed to embed into the plastic substrate,

(d) hardening said substrate and,

(e) repeating steps (b), (c) and (d) at least once whereby previouslyembedded particulate material further disperses in said substrate toprovide a substantially unagglomerated visible dispersion of saidmaterial in said substrate.

14. The method of claim 13 wherein the conductive particulate materialcomprises carbon black.

15. The method of claim 1 wherein the surface to be coated of saidsoftenable plastic substrate is rendered at least partially adhesive tosaid particulate material by softening during said coating.

16. The method of claim 10 wherein step (b) is accomplished a pluralityof times prior to each repeat of steps (c) and (d) to build up the layerof particulate material to no more than a monolayer.

17. The method of claim 11 wherein the photoconductive materialcomprises amorphous selenium.

18. The method of claim 1 wherein said softenable plastic material issubstantially electrically nsulating.

19. The method according to claim- 4 wherein said softenable plasticmaterial is substantially electrically insulating.

20. The method according to claim 7 wherein said softenable plasticmaterial is substantially electrically insulating.

21. The method according to claim 10 wherein said softenable plasticmaterial is substantially electrically insulating.

22. The method according to claim 11 wherein said softenable plasticmaterial is substantially electrically insulating.

23. The method according to claim 12 wherein said softenable plasticmaterial is substantially electrically insulating.

24. The method according to claim 13 wherein said softenable plasticmaterial is substantially electrically insulating.

25. The method according to claim 1 wherein said softenable plasticsubstrate is of a substantially uniform thickness of between a-bout 1 toabout 4 microns.

26. The method aceording to clair` 4 wherein said 27. The method ofclaim 5 wherein the plasti c substrate 's softened upon heating to-atemperature between about 60 to about 120 C. e I A 28. The methodaccording to claim 25 wherein steps (a) and (b) are accomplshed asufficent number of times so that partcles are dispersed in saidsoftenable substrate layer to between about A to about of the thicknessof said layer. 3

29. The method according to claim 26 wherein steps '(b) and (c) areaccomplshed a sufficient number of times so that particles are dispersedin said softenable substrate layer to between about fl to about of thethickness of said layer.

30. The method of claim 28 wherein said partculate material comprsesamorphous selenium.

33. 'The method of claim 1 whereir the diameter of the particulatematerial is less than about /2 the thickness of said softenablesubstrate.

34. The method `of claim 1 wherein the 'diameter of the particulatematerial is below about 0.7 micron References Cited I UNITED STATESPATENTS 2,716,048 8/1955 Young 117-17.5 2,909,443 10/ 1959 Wolinski 117-16 2,924,519 2/ 1960 'Bertelsen 117-175 3,192,0'43 6/1965 Metcalfe etal. 96- 15 3,244,546 4/1966 Cranch 117-175 3,085,025 4/1963- Eaton117--10 MURRAY KATZ, Primary Examiner R. M. SPEER, Assistant ExamnerUNTED STATES PATENT OFFCE CERTIMCATE m CORRECTION e Patent No. 3,67,282Dated June 20, 1972 Irventor(s) W. L. Go ffe 4 It is Certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below: v

F" I e *1 column 6, line 42, delete and irsert Column 79 line 3 qe te"Examples" and insert --Samples-- Signed and sealed *cs izt'day of June1973;

CSEAL) Attestz v EDWARD M.FLETCH-ER,JR. ROBERT GOTTSCHALK Att'estngofficer Commissioner of Patents

